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During the borax bead test, a glassy transparent bead is formed which gives characteristic colors wip Block Elements Chemistry Question

Question

During the borax bead test, a glassy transparent bead is formed which gives characteristic colors with transition metals. The blue bead formed when reacting with copper oxide ($CuO$) is chemically composed of:

Answer: C

💡 Solution & Explanation

Heating borax yields a glassy bead of sodium metaborate ($NaBO_2$) and boric anhydride ($B_2O_3$). The basic $CuO$ reacts with the acidic $B_2O_3$ to form Copper(II) metaborate, $Cu(BO_2)_2$, which exhibits a distinct blue color.

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